Access to particular areas or compartments of a helicopter, aircraft, vehicle or other application may be restricted by an access door. As one non-limiting example, an access door may restrict access to a vehicle's fuel tank, which can be subjected to significant pressure during a crash or other traumatic event. A properly sealed access door can help insulate the area/compartment housing the fuel tank from the rest of the vehicle and thus help contain any pressure rises or leaks within the area/compartment housing the fuel tank. The access door can also permit access to the fuel tank when required, such as during installation or maintenance of the fuel tank system.
Some access door assemblies include a ring that is bonded to the fuel tank and a door placed above and fixed to the ring using a plurality of fastening members, such as screws or bolts. Securing the fastening members in place axially seals the components of the access door assembly in the direction of the fastening members with the force transmitted by the fastening members. Manually securing each of the fastener members to fix the door relative to the ring is time consuming and takes approximately 10 or so minutes to complete, thus increasing installation and maintenance time. Moreover, use of a screwdriver or other suitable tool to fasten and unfasten the fastener members risks damage to the fuel tank. Further, the closing force and thus the sealing of the assembly can be diminished over the lifetime of the fuel tank as the door assembly is fixed and unfixed by screwing and unscrewing each of the fastener members.
In addition, whether a sufficient axial seal is created between the ring and the door depends in large part on the operator and whether the fastener members are positioned and tightened correctly. Because the fastener members maintain the closure of the door assembly and thus bear the brunt of the inner stresses (stresses from within the area/compartment of the access door assembly) and outer stresses (stresses external to the area/compartment that act on the access door assembly), the axial seal can be compromised and the resistance of the door assembly to both inner and outer stresses can be lowered if the assembly process is not performed correctly. This lowered resistance may not meet applicable resistance to crash standards required for certain uses of the access door.